Electrical distribution networks, such as the power grid conditions can be categorized by varying relationships between the current and voltage at various points of the network. Therefore, phasor measurement that provides information on both magnitude and phase of current and voltage at a point of measurement on the power grid has a significant importance for network operation. Such measurements can further be used for monitoring the performance of the power grid, monitoring and controlling power generation units, lines connecting stations and substations and used by protective relays or other devices distributed throughout the power grid. Power grids currently have a relatively significant amount of hardware supporting phasor measurement units (PMUs) on the power grid to provide phasor information based on voltage and current measurements at various points on the power grid.
There is a trend for future electrical power grids towards measuring and monitoring the phasors in a synchronized fashion based on the Institute of Electrical and Electronic Engineers (IEEE) C37.118 standard. Such synchronized phasors, also referred to as synchrophasors, typically need to be synchronized to about 1 micro-second (μs) or less across the power grid. To accomplish this by conventional methods, PMUs capable of synchronized measurements, are distributed throughout the power grid. Each PMU receives a common clock, reporting current, and voltage phasors at a sampling instance based on the received clock signal. The clock signal therefore must be delivered to each PMU with a relatively high level of Master Clock-to-PMU precision, such as for example, +/−500 nano-seconds (ns) across all PMUs on the grid. Typically clock signals from satellite systems are used for such purposes.
The use of synchronized phasor measurements can therefore require replacing legacy phasor measuring capable devices that use asynchronized sampling with phasor measuring capable devices that use synchronized sampling involving potentially significant investment.